Comment 2 for bug 246450

I've got the same problem actually, the problem is that flash keeps segfaulting, causing the gray box.

If you check dmesg you'll see something like this:

[28262.352742] npviewer.bin[13448]: segfault at 4 rip f6ee1d54 rsp ffc48b40 error 4
[28288.212763] npviewer.bin[13559]: segfault at 4 rip f6e3fd54 rsp ffbb1aa0 error 4

You don't need to reinstall flash, restarting firefox completely (close all instances of the browser) will solve the problem.

It would be great if this problem could be fixed, but I doubt it has anything to do with ubuntu, its more likely that the problem is
in the 64 bit version of the flash plugin.